A popular device for handling large amounts of information in a data processing system is an automated cartridge library. Automated cartridge libraries store and manage large numbers of standardized tape cartridges containing magnetic tape on which is recorded data. Typically, an automated cartridge library includes arrays of uniquely identified cells, each cell being formed to contain a tape cartridge. The cell arrays are effectively racks for holding a multitude of tape cartridges, each cell having some kind of identifying information, such as a bar code. A robotic arm having an optical system for selecting the correct cartridge is operable within the automated cartridge library to locate a particular cell, retrieve a tape cartridge from the particular cell, convey the tape cartridge to a tape drive, and insert the tape cartridge into the tape drive The tape drive is then operable to read or write data to the magnetic tape of the tape cartridge. In this way, a large number of tape cartridges are automatically accessible to a single tape transport mechanism. The operation of the automated cartridge library is typically controlled by a host computer working through a library control unit.
In some applications, such a large amount of data must be stored that it is desirable to employ more than one automated cartridge library in order to manage the large number of tape cartridges. Rather than repeating an entire automated cartridge library including all the necessary control units, the host computer, and the tape drive, it is desirable to link together multiple library storage modules. Each library storage module contains cell arrays and a robotic arm as described above but does not require additional host computers and need not contain a tape drive. Multiple library storage units are arranged adjacent one another and pass through ports are provided for passing tape cartridges from one library storage module to an adjacent library storage module. In this arrangement, the host computer can direct a library storage module not having a tape drive to pass a tape cartridge to an adjacent library storage module where it is picked up by the robotic arm of the adjacent library storage module and transported to and inserted in a tape drive of the adjacent library storage module.
A critical component in the use of an automated cartridge library is a tape cartridge access port. A tape cartridge access port is a port for tape cartridges to pass between the automated cartridge library and the outside environment. A tape cartridge access port, which is mounted on an automated cartridge library, loads tape cartridges into and retrieves tape cartridges from the automated cartridge library. Typically, tape cartridges are loaded onto a magazine and then the magazine is inserted through the tape cartridge access port. The tape cartridges are loaded onto the magazine with their front surfaces oriented toward the operator. The front surfaces of the tape cartridges contain information label such as bar codes. The cartridge access port then rotates the magazine, and thus the tape cartridges, so that the information labels face the interior of the automated cartridge library. Consequently, the tape cartridges can be accessed by the robotics of the automated cartridge library.
A problem with rotating or repositioning the magazine and the tape cartridges for presentation to the robotics of the automated cartridge library is that this creates unnecessary complexity. Further, a problem with typical tape cartridge access ports that are capable of loading multiple tape cartridges at a time in an automated cartridge library is that an operator may insert a body appendage instead of a tape cartridge magazine into the automated cartridge library and possibly damage the robotics inside the automated cartridge library.